1. Field of the Invention
The invention relates to a novel process for preparing alkoxypyrazine derivatives of the general formula: ##STR4## in which R.sup.1 denotes hydrogen, alkyl or aryl, R.sup.2 denotes hydrogen, alkyl, --CONH.sub.2, --COOR.sup.4, in which R.sup.4 denotes alkyl, or --C(NH)OR.sup.4, in which R.sup.4 is as defined above, and R.sup.3 denotes alkyl or aryl. Moreover, the invention relates to a novel process for preparing alkoxypyrazineamine derivatives of the general formula: ##STR5## in which R.sup.1 and R.sup.3 are as defined above.
2. Background Art
Both the alkoxypyrazine derivatives of the general formula Ia and the alkoxypyrazineamine derivatives of the general formula V are important intermediates for preparing pharmaceutically active compounds [Katritzky, Comprehensive Het. Chem.,Vol. 3, (1984), 179-197].
A number of processes for preparing pyrazine derivatives are known from the above-mentioned literature reference.
British Published Patent Application No. 922,725, for example, describes a process for preparing 3-methoxy-5-methylpyrazine-2-amine by reaction of 3-chloro-5-methylpyrazine-2-amine with sodium methoxide.